README, debian/control: add missing build-dependency on gettext
Android/Main: don't send resize to TopWindow before it gets created

Fixes nullptr dereference (TRAC #2575).
Android/Main: don't send pause/resume to TopWindow before it gets created

Fixes potential nullptr dereference (similar to TRAC #2575).
RowFormWidget: uniform row "available" checks in both loops

Previously, the checks for skipping unavailable rows were different
in the two loops inside UpdateLayout(), resulting in inconsistent
n_elastic counts, crashing the process with assertion failure (TRAC
#2533, #2538, #2562, #2563).
po: update German translation
po: update French translation
vagrant: Added basic vagrant environment

This will use an Ubuntu 12.04 base box and configure it to be able to
compile the UNIX target of XCSoar on it.
vagrant: Use NFS shared folders to speed up compilation